docs: def generate_default_filename(infile_path, is_cropped_file=True):
      """Generate the name of the default output file from the name of the input
      file.  The is_cropped_file boolean is used to indicate that the file has been
      (or will be) cropped, to determine which filename-modification string to
      use.  Function assumes that args has been set globally by argparse."""
  
      if is_cropped_file: suffix = prefix = args.stringCropped
      else: suffix = prefix = args.stringUncropped
  
      # Use modified basename as output path; program writes default output to CWD.
      file_name = os.path.basename(infile_path)
      nameBeforeExtension, extension = os.path.splitext(file_name)
      if extension not in {".pdf", ".PDF"}: extension += ".pdf"
  
      sep = args.stringSeparator
      if args.usePrefix: name = prefix + sep + nameBeforeExtension + extension
      else: name = nameBeforeExtension + sep + suffix + extension
  
      return name